1. Field of the Invention
The present invention relates to a semiconductor integrated circuit chip, a multilayer chip capacitor and a semiconductor integrated circuit chip package.
2. Description of the Related Art
A semiconductor integrated circuit chip such as a micro processor unit (MPU) chip is continuously increasing in operating frequency, and the integration density thereof is also increasing. For this reason, current consumption of the semiconductor integrated circuit chip is continuously increased, and its operation voltage is lowered. Thus, it becomes more difficult to suppress noise of a DC supply voltage, which occurs due to a sudden fluctuation of a load current of the semiconductor integrated circuit chip.
That is, as can be seen from the following equation, the target impedance (Ztarget) is being gradually lowered.Ztarget=Vp×AR/I=Vr/I where Vp represents a power voltage, AR represents an allowed ripple, I represents a current consumed by an MPU, and Vr represents an allowed ripple voltage.
In general, the allowed ripple voltage (Vr) ranges from about 5% to about 10% of a power voltage. The target impedance (Ztarget) must be met not just at a DC current (DC) but also at every frequency at which a transient current exists. In the case of a personal computer (PC) or a notebook computer, a transient current exists even in the very high frequency range because of the use of high-speed semiconductor integrated circuits, i.e., high-speed central processing units (CPUs). Thus, the target impedance must be satisfied even in a wide frequency range.
A decoupling capacitor can remove the voltage noise by supplying a current to the semiconductor integrated circuit chip at the time of the sudden fluctuation of the load current. However, even with the decoupling capacitor, it is not easy to meet the target impedance even at a high frequency. Therefore, there is a need for a method for maintaining an impedance of a power distribution network below the target impedance in a wide frequency range, particularly at the high frequency.